KIDAL, Mali (Reuters) - A Tuareg militant leader in the volatile north Malian city of Kidal was killed on Saturday when his car exploded barely 300 meters from a U.N. base where he had been talking with French and U.N. troops, a Reuters witness and officials said.

A Reuters cameraman saw the car still burning after the blast that killed Cheikh Ag Aoussa.

A spokeswoman for the U.N. Mali mission, Radhia Achouri, confirmed the incident, which is likely to further ignite tensions between rival pro and anti-government factions of ethnic Tuaregs in Kidal.

A spokesman for French forces in Mali did not immediately respond to a request for comment.

The Tuareg-led Coordination of Azawad Movements (CMA) and rival pro-government "Gatia" militia fighters have clashed sporadically since a power-sharing deal, in place since February, began to crumble. Up to 20 people were killed in two days of fighting between them in July.

Aoussa was a senior commander in a CMA-allied group.

A security source suggested Aoussa's death was the accidental result of running over a land mine. But Almou Ag Mohamed, spokesman for his HCUA militant group, said "it is clear an explosive was attached to his vehicle inside the camp."

The Tuaregs, nomadic pastoralists who have for centuries survived off trade crossing the Sahara and connecting Africa's interior with its Mediterranean coast, were at the heart of a 2012 uprising that threw Mali into chaos.

Their rebellion was swiftly hijacked by jihadists whom the French then intervened in 2013 to chase out.

A U.N.-backed peace deal between a plethora of Malian armed groups was supposed to draw a line under the violence that has torn apart Africa's third largest gold producer. Yet it has failed to stop worsening violence in the north and center of this vast, desert nation.

Mali's military pulled out of Kidal after clashes between the army and Tuareg rebels killed 50 soldiers there in 2014.